High voltage relay



2 Sheets-Sheet l INVENTOR Reuben Lee ATTORNEY R. LEE

HIGH VOLTAG E RELAY Original Filed Oct. 21, 1951 July 14, 1936.

WITNESSES.

R. LEE

HIGH VOLTAGE RELAY 2 Sheets-Sheet 2 July 14, 1936.

Original Filed Oct. 21, 1931 fiyz.

1 L 0- Reef/fier- INVENTOR WITNESSESI MV W/W Reuben Lee BY ATTORN Y Patented July 14, 1936 UNITED STATES PATENT OFFICE HIGH VOLTAGE RELAY Application October 21, 1931, Serial No. 570,147 Renewed December 3, 1935 10 Claims.

My invention relates to relay or control circuits and particularly to overload relays for the plate circuit of radio transmitter tubes.

In large radio transmitters, the plates of the amplifier tubes are maintained at a high potential, 18,000 volts for example. It is necessary to protect the amplifier tubes by connecting an overload relay in the plate circuit of each amplifier tube so that the plate potential will be removed from the tubes as soon as an overload occurs.

Since it is desirable to remove the plate voltage by interrupting a low voltage circuit rather than a high voltage circuit, it has been common practice to place the relay contacts in the 110 volt primary circuit of the plate transformer where they are near ground potential. These contacts were operated by the relay coil in the high voltage plate circuit by means of a rod of insulating material connecting the contacts to the solenoid of the relay coil. Because of the large difference in potential between the relay coil and the grounded contact points, this rod had to be long in order to provide the necessary insulation and because of its length, the moving parts of the relay were heavy, and the relay did not respond to an overload as quickly as it should.

An object of my invention is to provide means for actuating apparatus in a low voltage circuit in accordance with the condition of a high voltage circuit without employing insulating material between the apparatus in the two circuits.

A further object of my invention is to provide a relay for a circuit of the above-mentionel type which does not require an insulating rod between the high voltage circuit and the contacts in the low voltage circuit.

In practicing my invention, I mount a relay coil on a portion of the apparatus which is at high potential and provide a shutter actuated by the armature of the relay coil for intercepting a light beam upon the occurrence of an overload. Until the light beam is intercepted, it strikes the photoelectric cell of a photo-electric cell relay circuit which controls the contacts in the low voltage circuit to be opened. Assoon as the overload occurs and the light beam is intercepted, the photo-electric cell circuit opens the contacts in the low voltage circuit to remove the voltage from the plate of the amplifiers.

Other features and advantages of my invention will appear from the following description taken in connection with the accompanying drawings in which Figure 1 is a circuit diagram of an amplifier of a radio transmitter embodying my invention,

Fig. 2 is a View showing the physical arrangement of the apparatus illustrated in Fig. 1, 5 Fig. 3 is a View taken on the line III-III of Fig. 2.

In Fig. l is shown the last two amplifier stages of a large radio transmitter. The first amplifier stage comprises a single tube lEl having a 10.

grid H, a filament i2 and a plate It. The power amplifier stage comprises four tubes l4 connected in parallel, each tube having a filament IS, a grid i6 and a plate IT. The filaments l2 and I5, which are connected to ground, are supplied with 5 current from the line. I8. The output circuit of the first amplifier stage is connected to the input circuit of the last stage by means of a tuned circuit 19 comprising a condenser 20 and an inductance coil 2! and a coupling condenser 22. 20 The grids I6 of the power amplifier are connected to the filaments I5 through a resistor 23 and a biasing battery 24. The output of the power amplifier feeds into a tank circuit 25 comprising an inductance coil 26 and variable condenser 2i. 25 The tank circuit 25 is coupled to the antenna 28 and ground through the coupling condensers 29 and 38, respectively.

A high voltage is supplied to the plates ll of the power amplifier from the rectifier and filter 30 unit 3!. Energy is supplied to this unit from the 110 volt line 32, one side of which is connected to ground. The low voltage supply circuit for the amplifier plates I! may be traced from one side of the line 32, through the conductor 34, contact 35, armature 36, contact 37, conductor 38, through the input circuit of the rectifier and filter unit 3! and through conductor 39 to the other side of the line 32.

In the plate circuit of each power amplifier 40 tube I4 is connected the coil 40 of an over-voltage relay 4!, the upper ends of the coils 40 being connected to the tank circuit 25 through a conductor 9. A shutter 42 is attached to each armature 43 of the relays 4i and is so positioned that when an overload occurs, it is pulled up into the path of a beam of light 44 which is supplied from an incandescent lamp 45 surrounded by a shield 46 having an opening 8 therein.

So long as the light beam 44 is not intercepted, it strikes the photo-cell 41 of a photo-cell relay circuit. This circuit comprises a three-electrode vacuum tube 48 having a filament 49, a grid 59 and a plate 5 I. The filament 49 is supplied with current from the 110 volt circuit 32 through a 110 volt filament transformer 52. The plate 5! is supplied with an alternating current voltage by means of a transformer 53 which has its primary winding 54 connected to the 110 volt line 32.

The plate 5! is connected to the upper end of the secondary winding 55 through a relay coil 56. When current flows through coil 56, the relay armature 55 is pulled down to open the circuit leading to the rectifier and filtering unit 3 I.

The filament i9 is connected through a conductor 58 to the secondary Winding 55 at a point intermediate its ends. The grid 55 is connected to the lower end of the secondary winding through a resistor 59, a condenser 60 and conductor 6 I.

The cathode 62 of the photo-electric cell Al is connected to the grid 55 by means of conductor 63. The anode 65 of the photo-electric cell is connected to the anode 5! by means of conductor 55. While the constants of the circuit are not critical, the resistor 59 preferably has a value of from 2 to 5 megohms, and condenser 55 a value of about .01 mfds. The condenser 55 may be omitted if desired.

The relay coil 55 is shunted by a condenser 66 in order to maintain steady direct current therethrough.

As soon as an overload occurs in any of the power amplifier tubes its relay 4! operates to pull up the shutter 42 and intercept the beam of light M. This causes current to fiow in the plate circuit of the tube 58 and the armature 35 is pulled down to open the input circuit of rectifier and filter unit 3 l.

The physical arrangement of the apparatus illustrated in Fig. 1 will be better understood by referring to Figs. 2 and 3. The power tubes M are of the water-cooled anode type having metal cooling jackets Bl surrounding and in electrical contact with the anode or plates ll and supplied with cooling liquid through a rubber hose B8. The tubes are mounted in vertical position on a metal panel 59 by means of blocks 10 of insulating material and straps 16. The panel 59 is supported by means of an insulator H at each corner, these insulators being mounted on a wall or on a panel. It should be noted that While the plates ll and cooling jackets Bl are insulated from the panel 69, this insulation need not be for a high voltage.

Each overload relay 4! is mounted on the metal panel 69 by means of a strap 12. Each relay coil 40 has one terminal connected to the plate ll of the power tube it is to protect through a conductor l3 and a cooling jacket Bl.

The light source 45 for the photo-electric cell relay is preferably mounted upon a separate support in order to keep its low voltage supply circuit away from the high voltage circuit. The photocell relay circuit is indicated by the box !4. The photo-cell Al of this circuit is mounted on the path of the light beam 44 and surrounded by a light shield 15.

Obviously, other photo-cell relay circuits may be substituted for the one illustrated.

Various other modifications may be made in my invention without departing from the spirit and scope thereof, and I desire, therefore, that only such limitations shall be placed thereon as are imposed by the prior art and are set forth in the appended claims.

I claim as my invention:

1. In a system comprising a plurality of vacuum tubes connected in parallel, each tube having a solenoid winding connected in its anode circuit, means including a light-responsive relay for opening a low-voltage circuit which supplies high-voltage to said anodes, a light source which normally projects a beam of light to said light-responsive relay, and means actuated by said solenoid windings for intercepting said beam of light.

2. In a radio system comprising a plurality of amplifier tubes connected in parallel, means for supplying a high voltage to the anodes of said tubes, said means including a low-voltage circuit, a normally inactive light-responsive relay adapted to open said low-voltage circuit upon actuation, and means responsive to overloads on any of the anode circuits of said tubes for actuating said light-responsive relay.

3. In a system of the radio type, a power amplifier having input and output circuits, a low potential circuit, means for changing said low potential to one of a relatively high value and applying said high value potential to said output circuit, a solenoid operatively connected to said output circuit, a circuit opening device located in said low potential circuit, a light responsive relay operatively connected to said circuit opening device for normally maintaining said circuit opening device in its closed circuit state, and means controlled by said solenoid for altering the condition of said light responsive relay to cause the operation of said circuit opening device during overloads on said power amplifier.

4. In combination, an electrical circuit of dangerously high potential, a low voltage circuit physically removed from said high voltage circuit, a light reactive element in said low voltage circuit, a light source associated with said light reactive element, means in said high voltage circuit, operable at a value which value would constitute an overload in said high voltage circuit, for altering the amount of light from said source to said light reactive element to change the condition of said low voltage circuit, said low voltage circuit being adapted to effectively remove the power from said high voltage circuit upon such a change in said low voltage circuit.

5. In combination, an electrical circuit at a dangerously high potential above ground potential, a low voltage circuit electrically insulated for high potential from said high voltage circuit, a light reactive element in said low voltage circuit, a light source associated with said light reactive element, means electrically connected in said high voltage circuit, operable at a value which value would constitute an abnormal electrical condition insaid high voltage circuit, for altering the amount of light from said source to said light reactive element to change the condition of said low voltage circuit, said low voltage circuit being adapted to effectively remove the power from said high voltage circuit upon such a change in said low voltage circuit.

6. In combination, an electrical circuit at a dangerously high potential above ground potential, a low voltage circuit electrically insulated for high potential from said high voltage circuit, a light reactive element in said low voltage circuit, a light source associated with said light reactive element, means electrically connected in said high voltage circuit, operable at a value which value would constitute an abnormal electrical condition in said high voltage circuit, for decreasing the amount of light from said source which falls on said light reactive element to change the condition of said low voltage circuit,

said low voltage circuit being adapted to effectively remove the power from said high voltage circuit upon such a change in said low voltage circuit.

7. In combination, a main electrical circuit having a source of a dangerously high voltage therein, a low voltage circuit electrically insulated for high potential from said high voltage circuit, a light reactive element in said low voltage circuit, a light source associated with said light reactive element, means electrically connected in said main high voltage circuit, operable in response to a predetermined electrical condition in said main high voltage circuit, for altering the amount of light from said source to said light reactive element, said low voltage circuit being operatively controlled from said main high voltage circuit through the beam of light falling on said light reactive element.

8. In combination, a main electrical circuit having a source of a dangerously high voltage of the order of several thousand volts therein, a low voltage electrical circuit insulated for high potential of the order of several thousand volts from said main electrical circuit, a light reactive element connected to control one of said electrical circuits, a light source associated with said light reactive element, and means connected in the other of said electrical circuits operable to alter the amount of light from said source falling on said light reactive element, said circuit to which the light reactive element is connected being thereby controlled through the beam of light falling on said light reactive element.

9. In combination, a main electrical circuit having a source of a dangerously high voltage of the order of several thousand volts therein, a low voltage electrical circuit insulated for high potential of the order of several thousand volts from said main electrical circuit, a light reactive element connected to control one of said electrical circuits, a light source associated with said light reactive element, and a plurality of means in the optical path between said light source and said light reactive element, each of said means being operable independently of the others to alter the amount of light from said source falling on said light reactive element, and said circuit to which the light reactive element is connected being thereby controlled through the beam of light falling on said light reactive element.

10. In combination, a main electrical circuit having a source of a dangerously high voltage therein, a low voltage circuit electrically insulated for high potential from said high voltage circuit, a light reactive element in said low voltage circuit, a light source associated with said light reactive element, a plurality of means electrically connected to the high voltage circuit and positioned in the optical path between said light source and said light reactive element, each of said means being operable independently of the operation of the others in response to a predetermined electrical condition to alter the amount of light reaching said light reactive element, and said low voltage circuit being operatively controlled by such a change in the amount of light reaching the light reactive element.

REUBEN LEE. 

